In the past, since the sensitivity of the touch control for touch panels is not high enough, the touch-panel screens only appear as the display devices with larger areas for the touch-control commands on the screen, e.g. ticket issuing machines, vending machines, tour information machines, etc. Most display devices, e.g. computer monitors, notebook computers, etc., still adopt the mice with much higher control sensitivity. As the technologies of the touch panels are continuously advancing, the sensitivity of the touch control has been raised, and the technologies of dual-point touch controls appear and bring great convenience for users. Thus, the touch panels are gradually and widely applied to the portable display devices, e.g. tablet computers, touch pad, smart mobile phones, etc., and become widely popular to most users.
Since the portable display devices are expected to be carried by users often, all the users hope that these devices can be as slim as possible. Thus, there is a trend in the industry to adopt the design of a single piece of glass to replace the conventional design of two pieces of glass for the manufactures of touch glass components so as to reduce the thickness and weight of the touch display devices. For the single glass design, the structures with touch control function are fabricated right on the internal surface of the originally required cover glass. However, interference mura frequently appears around the area close to the edge of the touch panel for the current single glass designs and seriously deteriorates the visual performance of the touch panels. On the other hand, the pictures of the touch panels manufactured by the prior art frequently have the problem of color shift that the colors of the pictures are distorted. Especially for the displayed pictures with the colors of human skins or the colors familiar to the public, e.g. yellow color taxi, the color shift would seriously affect the visual performance for viewers.
From the above, it can be understood that the visual performance and the structures of the touch panels need to be improved. For overcoming the above mentioned problems occurring in the prior art, novel touch display devices able to solve the mentioned problem have been developed after a lot of researches, analyses and experiments by the inventors.